The invention relates to an air guidance unit for mounting into a cut-out of a switch-gear cabinet wall, comprising an air guidance housing and a fan assembly that can be detachably connected thereto, the air guidance housing comprising one or more blocking studs, the fan assembly comprising closure receptions each having a block-inq section into which the blocking stud can be swiveled, a detachable locking piece immobilizing the fan assembly in the mounting position of the fan assembly, wherein the fan assembly comprises two fixing sides, the fixing sides comprising the closure receptions with blockings section and wherein the fan assembly can be selectively fixed at the air guidance housing by means of the fixing sides in operating positions rotated by 180 degrees. In a maintenance situation, merely the locking piece must be unlocked. Then, the fan assembly can be swiveled away from the blocking stud and can be removed. A new fan assembly can then be quickly and simply replaced in a reversed assembly sequence. Such an air guidance unit is known from WO 2007/090804 A2. Other air guidance units are known from U.S. Pat. No. 5,117,656 A, EP 0 242 342 A1, US 2008/037216 A1 and DE 20 2006 015 789 U1.
Air guidance units of this type are, for example, used in switchgear cabinet construction. The air guidance housing is installed in a cut-out of a switchgear cabinet wall. The fan assembly generally includes an electric motor and a fan which sucks ambient air, conveys it through the air guidance housing and blows it into the interior of the switchgear cabinet. In an alternative construction variant, the air conveying direction is reversed, where air is sucked from the interior of the switchgear cabinet and is blown out to the ambient through the air guidance housing. In a maintenance situation, the defective fan assembly is separated from the air guidance housing and is replaced by a new one.